Cat Fountain Filter Replacement - Activated Coconut Carbon is used. High quality coconut shells are used as raw material. there are cationic components, which have the function of cleansing and activating. It can more evenly filter the water flow of impurities to achieve a higher quality water source. Efficient Triple Filtration - Cat water fountain filters made from premium quality filters and activated carbon, and an ion exchange resin. The cat filter fountain can filter hair, heavy metals and improve the taste of water so that pets can drink clean and fresh water all day. ensure that every drop is healthy, making the water cleaner and fresher. Filter Replacement Frequency - Each of the filters in the 6 Pack Cat Water Dispenser is individual so each one is costs. We recommend changing them every 2-4 weeks to keep the water fresh and clean. If multiple pets use the water dispenser, more frequent changes will be required. Perfect match - Filter size is 5 x 5 inches, inner circle